Zodiac: It is the broad
band or belt in the heavens extending 9 degrees on either side
of the ecliptic and known as Bhachakra or the Circle of Light.
It is a circle and as such it knows no beginning or end.

The Ecliptic: The ecliptic
is the Sun's path. This is known as Apamandala or Ravimarga
in Sanskrit. It passes exactly through the centre of the zodiac
longitudinally.

Ascendant: Ascendant
or Lagna is that point of the ecliptic which at any time is
on the eastern horizon. As all the twelve signs will rise in
the eastern horizon owing to the movement of the earth, there
will be twelve lagnas each day. Lagna is therefore to mean,
the Rising Sign at the time of the birth of the native.

Bhava: The houses where
the twelve zodiacal signs / stars are placed according to their
longitude. The most powerful point in a Bhava is its Madhya
Bhaga or midpoint whereas the first point is the most powerful
in a western house.

Horoscope: A diagram
showing the observation of Sky and the planets at certain moment
especially at the time of birth of a person and invoking a study
of the influence of the celestial bodies on human affairs as
well as their mudane world according to the configuration of
planets.

Latitude: The latitude
of the planets is its distance north or south of the equator
measured as an angle, on its own terrestial meridian. It is
reckoned in degrees, minutes and seconds from 0 degrees to 90
degrees northwards or southwards according to the place lies
in the northern or southern hemisphere. Celestial Latitude is
the angular distance of a heavenly body from the ecliptic.

Longitude: The longitude
of the place is its distance east or west of the meridian or
Greenwich measured as an angl. It is expressed in Degrees, Minutes
and Seconds, east or west of Greenwich are to where the place
lies. It is also reckoned in time at the rate of 24 hours for
360 degrees or 4 minutes to a degree.

The Signs of the Zodiac:
The ecliptic is divided into twelve equal compartments, the
signs of the zodiac, each being thirty degrees in extent. Each
sign has its own peculiar qualities attributed to it by the
ancient Maharshis, after careful and profound observation and
meditation.

Constellation: The ecliptic
is marked by twenty-seven constellations or nakshtras, often
called lunar mansions, because the Moon is brought into special
connection with them, as traversing twenty-seven constellations
and making a complete round of the ecliptic in a lunar month.
Each constellation contains four padas or quarters and each
quarter is equal to 3 1/3 degree of the celestial arc (rekha).

The Planetary System:
This is otherwise known as the solar system, headed by the most
glorius Sun - the Jagatchakshu - consists of seven important
planets (including the Sun himself). All the planets, save the
central luminary, are held by the gravitation of the Sun and
they all revolve round him, the period of revolution varying
with reference to each planet. Along with these are included
Rahu and Ketu - considered as Apakashaka grahas or shadowy planets.

Retrogression and Acceleration:
When the distance of any one planet from the Sun exceeds a particular
limit, it becomes retrograde, i.e., when the planet goes from
perhelion (the part of a planet's orbit most distant from the
Sun) as it recedes from the Sun, it gradually loses the power
of the Sun's gravitation and consequently, to gain it, it retrogrades.
When the planet comes from aphelion to perhelion, nearer and
nearer to the Sun the gravitation of the Sun grows more and
more powerful, so that the velocity of the planet is accelerated.

Lunar Year: This consists
of twelve lunar months. The name of each lunar month is given
according to the constellation falling on the Full Moon day
of the particular month. The lunar month is generally of 27
- 29 days, during which the Moon, the fastest moving planet
travels along all the the signs of the Zodiac.

Solar Year: This consists
of twelve solar months. The Sun takes 365 days and 6 hours to
complete one rotation round the zodiac which is a complete solar
year. The twelve solar months are Mesha, Vrishaba, Mithuna,
Kataka, Simha, Kanya, Thula, Vrischika, Dhanu, Makar, Kumbh
and Meena. The year begins roughly around April 20th while the
lunar year starts around March 15th.

Almanac: Otherwise known
as Panchang or five parts. The Hindu Almanac furnishes details
of Thithi, Vara, Nakshatra, Yoga and karana. Vara is
one of the seven days of the week, Nakshatra is one of
the 27 constellation of the celestial sphere, Thithi
is one of the 15 days preceeding New Moon or Full Moon.

Siderial Time: This is
the time taken by the Earth to make one full rotation. It is
not exactly 24 hours but goes on changing according to increase
or decrease in the duration of the days and nights. It is called
Vernal Equinox time and it is a measure of Earth's rotation.

Standard Time: Originally
each city of India used to maintain the local mean time of her
own and the Almanacs used to mention the local apparent mean
Moon. In order to bring uniformity for the purpose of astronomical
calculations and ascertain position of planets a standard time
was adopted keeping the longitude 82o 32' E w.r.t
Greenwich Mean Time which in India is exactly 5 Hrs. 30 Min.
ahead of GMT.